In U.S. Pat. No. 3,877,273 assigned to the same assignee as the present invention, there is described an arrangement for cold rolling finished gear teeth on the smooth periphery of a metal gear blank. The periphery of the gear blank is forcefully engaged by the circumference of a pair of gear-forming rolls. The rolls have teeth which are the conjugate in profile to the teeth to be formed. If the blank is rolled between the opposing gear-forming rollers under pressure which squeezes the blank between the rollers, the rolling action produces an inelastic deformation of the blank material into desired gear profile.
To achieve satisfactory results, the gear blank must be very accurately positioned between the rollers before the rollers are brought into contact with the gear blank. The axis of the blank must be held exactly parallel to the axis of rotation of the two rolls. However, once the blank is clamped between the gear rolls, the holder must no longer impose any restraints on the movement of the blank as it is rolled between the forming rolls. In addition, the rolls must be accurately indexed in relation to each other. Only if the blank is properly positioned relative to the forming roll at the time the workpiece is first engaged by the rolls and if the rolls are properly indexed with respect to each other will the trace of teeth impressions on the blank defined by one of the rolls register exactly with the trace defined by the forming teeth of the other roll. In addition the force of engagement of the forming rolls with the workpiece must be increased gradually from a very light pressure to the required cold forming of the finished gear teeth.